In a magnetic transducer, a given combination of pole tip and gap dimensions, film thickness and yoke geometry using high saturation magnetization and high permeability alloy have proven to be superior for high density recording, especially with respect to the ability to write high coercivity recording medium. A typical high saturation magnetization alloy is nickel-iron in the ratio of 45 percent nickel to 55 percent iron. A common high permeability alloy is permalloy which is a nickel-iron alloy having approximately 80 percent nickel and 20 percent iron. At the location where the pole tip region initially saturates, the high saturation magnetization 45/55 NiFe alloy permits more flux to be transmitted to the pole tips and to the recording media. Typical thin film transducer head structures have a particular yoke structure formed of a single magnetic layer while having its pole structure wider and thicker in the back gap region and narrower and thinner in the pole tip region. Such a structure is shown in U.S. Pat. No. 4,190,872 issued to Jones, et al., and assigned to the assignee of the present invention.
In the single layered nickel-iron films, the magnetic film structures are constructed of a laminated structure having a plurality of magnetic layers. The Kumasaka, et al., U.S. Pat. No. 4,610,935, entitled "Magnetic Film Structure" describes a laminated thin film structure having a plurality of magnetic layers containing iron or cobalt as the principal constituent and an intermediate very thin layer of a nickel and iron alloy or an amorphous magnetic alloy. A plurality of the laminated layers can be placed together, separated by a nonmagnetic isolation layer. The magnetic film structure is said to have high saturation magnetic induction and a low coercive force.
A Kumasaka, et al., U.S. Pat. No. 4,748,089, entitled "Multilayered Ferromagnetic Amorphous Alloy Film and Magnetic Head Employing the Same," describes a magnetic head having at least a portion of its pole pieces formed of a multilayered film of a main film and a spacer lamination. The main magnetic film is a binary system amorphous alloy with its principal component of a material selected from the group consisting of cobalt, iron and nickel. The spacer magnetic film is made from a polycrystalline or amorphous ferromagnetic material. No nitrogen is included as a component of either magnetic layer.
A European patent publication 0247868 to Kobayashi, et al., entitled "Magnetic Film and Magnetic Head Using the Same," having a publication date of Dec. 2, 1987, describes a magnetic film having ferromagnetic layers of nickel and iron alternated with a layer of iron and one or more elements selected from the group of boron, nitrogen, carbon and phosphorus which are elements that are interstitially soluble in iron. A multilayer magnetic film made of the alternating layers is said to enable an increase in the relative permeability.
A U.S. Pat. No. 3,124,490, issued to Schmeckenbecher, entitled "Variable Access Magnetic Films," describes magnetic films having a small amount of an interstitial element which is capable of occupying positions in the interstices in the film lattice. Carbon, nitrogen, boron, phosphorus and sulfur are mentioned as suitable interstitial elements. The percentage of interstitial elements is described to be in the range from 0.5 percent to 4.5 percent. The films made according to this patent are said to exhibit properties of variable access and variable magnetization threshold.
An object of the present invention, therefore, is to provide a storage subsystem having an enhanced magnetic transducer that is useful for accessing different data tracks of a storage medium.